U.S. patent number 6,599,431 [Application Number 09/880,761] was granted by the patent office on 2003-07-29 for purifying apparatus for contaminated water and ground water and method thereof.
This patent grant is currently assigned to Canon Kabushiki Kaisha. Invention is credited to Kinya Kato, Masahiro Kawaguchi, Akira Kuriyama.
United States Patent |
6,599,431 |
Kawaguchi , et al. |
July 29, 2003 |
**Please see images for:
( Certificate of Correction ) ** |
Purifying apparatus for contaminated water and ground water and
method thereof
Abstract
A method and an apparatus for purifying water including
groundwater contaminated with a pollutant such as organohalogenated
compounds are provided. The contaminated water is purified by
aeration to expel the pollutant into gas phase, and the pollutant
containing gas is then mixed with a chlorine-containing gas under
light irradiation to decompose the pollutant, where the
chlorine-containing gas may generated from functional water by
aeration.
Inventors: |
Kawaguchi; Masahiro (Kanagawa,
JP), Kato; Kinya (Kanagawa, JP), Kuriyama;
Akira (Kanagawa, JP) |
Assignee: |
Canon Kabushiki Kaisha (Tokyo,
JP)
|
Family
ID: |
26594131 |
Appl.
No.: |
09/880,761 |
Filed: |
June 15, 2001 |
Foreign Application Priority Data
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Jun 16, 2000 [JP] |
|
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2000-181840 |
Dec 20, 2000 [JP] |
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2000-386970 |
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Current U.S.
Class: |
210/748.09;
204/232; 204/554; 210/150; 210/188; 210/192; 210/218; 210/748.13;
210/806 |
Current CPC
Class: |
B01D
53/007 (20130101); B09C 1/002 (20130101); C02F
1/20 (20130101); C02F 1/32 (20130101); C02F
1/4674 (20130101); C02F 2101/36 (20130101); C02F
2103/06 (20130101) |
Current International
Class: |
B01D
53/00 (20060101); B09C 1/00 (20060101); C02F
1/20 (20060101); C02F 1/461 (20060101); C02F
1/467 (20060101); C02F 1/32 (20060101); C02F
001/30 () |
Field of
Search: |
;210/748,691,806,150,188,192,218,170 ;204/554,232 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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605882 |
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Dec 1993 |
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EP |
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49-100846 |
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Sep 1974 |
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JP |
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54-66376 |
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May 1979 |
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JP |
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1-180293 |
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Jul 1989 |
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JP |
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6-31135 |
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Feb 1994 |
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JP |
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8-243351 |
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Sep 1996 |
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JP |
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9-299753 |
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Nov 1997 |
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JP |
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10-180040 |
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Jul 1998 |
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JP |
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WO 94/03399 |
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Feb 1994 |
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WO |
|
Primary Examiner: Hoey; Betsey Morrison
Attorney, Agent or Firm: Fitzpatrick, Cella, Harper &
Scinto
Claims
What is claimed is:
1. A purifying apparatus for contaminated water comprising: an
aerator in which a contaminated water containing a pollutant is
aerated with a gas to generate a gas containing the pollutant; a
chlorine-containing gas generator that generates a
chlorine-containing gas; a mixing section where the
pollutant-containing gas generated from the contaminated water and
the chlorine-containing gas generated in the chlorine-containing
gas generator are mixed; and light-irradiation means for
irradiating the mixed gas with light to decompose the pollutant
contained in the mixed gas.
2. The purifying apparatus according to claim 1, wherein the
apparatus is constituted such that the aerator is in a well.
3. The purifying apparatus according to claim 1, wherein the
chlorine-containing gas generator is a unit using a chlorine
cylinder.
4. The purifying apparatus according to claim 1, wherein the
chlorine-containing gas generator comprises a means for contacting
air with a functional water so that a chlorine-containing gas is
generated by aeration.
5. The purifying apparatus according to claim 4, wherein the
chlorine-containing gas generator comprises a water tank, means for
generating functional water, means for introducing air into the
water tank, means for discharging a chlorine-containing gas
generated, and means for discharging the functional water used for
generating a chlorine-containing gas.
6. The purifying apparatus according to claim 5, wherein the means
for generating functional water comprises a water tank, means for
feeding an electrolyte-containing water into the water tank, and a
pair of electrodes and a power source to apply an electric
potential to the electrolyte-containing water in the water
tank.
7. The purifying apparatus according to claim 4, wherein the means
for generating functional water comprises a water tank, means for
feeding an aqueous solution of a hypochlorite into the water tank,
and means for feeding at least either of an inorganic acid and an
organic acid into the water tank.
8. The purifying apparatus according to claim 4, wherein the
chlorine-containing gas generator comprises means for sending air
to the surface of the functional water.
9. The purifying apparatus according to claim 8, wherein the
functional water is generated near an anode of a pair of electrodes
by electrolyzing an electrolyte solution in a water tank, the
chlorine-containing gas generator comprises means for introducing
air near the anode in the water tank.
10. The purifying apparatus according to claim 4, wherein the
chlorine-containing gas generator comprises means for contacting
small droplets of the functional water with air.
11. The purifying apparatus according to claim 10, wherein the
means for contacting is a nozzle to spray the functional water.
12. The purifying apparatus according to claim 4, wherein the
chlorine-containing gas generator comprises means for aerating the
functional water with air.
13. The purifying apparatus according to claim 12, wherein means
for aerating the functional water with air is a bubbler.
14. The purifying apparatus according to claim 12, wherein the
functional water is generated near an anode of a pair of electrodes
by electrolyzing an electrolyte solution in a water tank, the
chlorine-containing gas generator comprises means for introducing
air near the anode in the water tank.
15. The purifying apparatus according to claim 4, further
comprising a means for introducing outside air that does not
contain the pollutant.
16. The purifying apparatus according to claim 4, further
comprising a means for directly introducing the
pollutant-containing gas into the chlorine-containing gas
generator.
17. The purifying apparatus according to claim 4, wherein the
purifying apparatus further comprises means for irradiating the
functional water that was used for generating a chlorine-containing
gas and discharged from the chlorine-containing gas generating
unit.
18. The purifying apparatus according to claim 4, wherein the
chlorine-containing gas generator and the mixing section are
integrated to constitute a decomposition treatment tank, where a
chlorine-containing gas generation region is present at the bottom
of the treatment tank, and occupies 5 to 30% by volume of the
treatment tank.
19. The purifying apparatus according to claim 1, wherein the
mixing section is bag-shaped variable in shape and volume, and
mixing is carried out in the mixing section.
20. The purifying apparatus according to claim 19, wherein the
bag-shaped mixing section has a bellows constitution.
21. The purifying apparatus according to claim 19, wherein the
purifying apparatus has an outer container covering the bag-shaped
mixing section.
22. The purifying apparatus according to claim 21, wherein the
irradiation unit is provided between the bag-shaped mixing section
and the outer container.
23. The purifying apparatus according to claim 1, further
comprising means for directly sending at least part of the
pollutant-containing gas obtained by aerating the contaminated
water into the mixing section.
24. The purifying apparatus according to claim 1, wherein the light
irradiated from the light-irradiation unit contains light of a
wavelength range of 300 to 500 nm.
25. The purifying apparatus according to claim 1, wherein
irradiation is carried out at a light intensity of 10
.mu.W/cm.sup.2 to 10 mW/cm.sup.2.
26. The purifying apparatus according to any one of claims 1, 2-6,
7, 8-15, 16, 17-23, 24 and 25, wherein the purifying apparatus
further comprises a second mixing section into which a gas
discharged from the first mixing section after treatment is
introduced; a second light-irradiation means to irradiate the gas
in the second mixing section: and discharging means for discharge
the further treated and decomposed gas from the second mixing
section.
27. The purifying apparatus according to claim 1, wherein the
apparatus further comprising an exhaust unit to exhaust a
decomposed gas from said section.
28. A method for purifying contaminated water comprising the steps
of: obtaining a pollutant-containing gas by aerating a contaminated
water containing a pollutant; obtaining a chlorine-containing gas;
mixing the pollutant-containing gas and the chlorine-containing gas
to form a mixed gas; decomposing the pollutant in the mixed gas by
irradiating with light the mixed gas introduced into a treatment
region in a treatment tank; and discharging the mixed gas after
decomposition treatment from the treatment region.
29. The purifying method according to claim 28, wherein the step of
introducing a chlorine-containing gas is a step of generating a
chlorine-containing gas by bringing air into contact with a
functional water that can generate a chlorine-containing gas by
aeration.
30. The purifying method according to claim 29, wherein the step of
generating a chlorine-containing gas comprises the steps of:
generating the functional water; supplying the functional water
into a water tank; introducing air into the water tank to generate
a chlorine-containing gas; discharging the chlorine-containing gas;
and draining off the functional water used for generating a
chlorine-containing gas.
31. The purifying method according to claim 30, wherein the step of
generating the functional water comprises the steps of: feeding a
water containing an electrolyte into a water tank; and applying an
electric potential to the electrolyte-containing water in the water
tank.
32. The purifying method according to claim 30, wherein the step of
generating a functional water comprises the steps of: feeding an
aqueous solution of a hypochlorite into a water tank; and feeding
at least one of an inorganic acid and an organic acid into the
water tank.
33. The purifying method according to claim 30, wherein the step of
generating a chlorine-containing gas from a functional water is a
step of blowing air to the surface of the functional water.
34. The purifying method according to claim 30, wherein the step of
generating a chlorine-containing gas from a functional water is a
step of bringing small droplets of the functional water into
contact with air.
35. The purifying method according to claim 30, wherein the step of
generating a chlorine-containing gas is a step of aerating the
functional water with air.
36. The purifying method according to claim 35, wherein the step of
aerating the functional water is carried out by bubbling.
37. The purifying method according to claim 29, wherein the
purifying method comprises a further step of irradiating with light
the functional water that was used in the step of generating a
chlorine-containing gas.
38. The purifying method according to claim 29, wherein a chlorine
generating region where the step of generating a chlorine
containing gas, and a treatment region where the step of
decomposing the pollutant is carried out are integrated in one
treatment tank, where a chlorine-containing gas generation region
is present at the bottom of the treatment tank, and occupies 5 to
30% by volume of the treatment tank.
39. The purifying method according to claim 28, wherein at least
part of a pollutant-containing gas obtained by the step of aerating
the pollutant-containing water is directly sent into the treatment
region.
40. A purifying apparatus for contaminated water, comprising: an
aerator in which a contaminated water containing a pollutant is
aerated with a gas to generate a gas containing the pollutant; a
gas generator that generates a gas that generates radicals under
light-irradiation; a mixing section where the pollutant-containing
gas generated from the contaminated water and the gas generated in
the gas generator are mixed to obtain a mixed gas; and a
light-irradiator that irradiates the mixed gas with light to
decompose the pollutant contained in the mixed gas wherein the gas
used to aerate the contaminated water is different from the gas
that generates radicals under light-irradiation.
41. A method for purifying contaminated water comprising the steps
of: obtaining a pollutant-containing gas by aerating a contaminated
water containing a pollutant; obtaining a gas that generates
radicals under light-irradiation; mixing the pollutant-containing
gas and the gas that generates radicals to form a mixed gas; and
decomposing the pollutant in the mixed gas by irradiating with
light the mixed gas wherein the gas used to aerate the contaminated
water is different from the gas that generates radicals under
light-irradiation.
42. An apparatus for purifying contaminated water, comprising: a
gas supplier supplying a first gas into a contaminated water to
generate a second gas containing a pollutant from the contaminated
water; a mixing section to get a mixed gas by mixing the second gas
and a third gas that generates radicals under light-irradiation;
and a light-irradiation unit that irradiates light to the mixed gas
wherein the first gas is different from the third gas.
43. A method for purifying contaminated water, comprising the steps
of: supplying a first gas into a contaminated water to generate a
second gas containing a pollutant from the contaminated water;
mixing the second gas and a third gas that generates radicals under
light-irradiation to form a mixed gas; and irradiating light to the
mixed gas to decompose the pollutant in the mixed gas wherein the
first gas is different from the third gas.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for purifying
contaminated water or contaminated ground water and to a method of
effectively purifying contaminated water or contaminated ground
water by using the apparatus.
2. Related Background Art
With the recent advances in industrial technologies, a large amount
of halogenated aliphatic hydrocarbon compounds (for example,
chlorinated ethylene, chlorinated methane and others) have been
used and their disposal and treatment have become a serious
problem. Most of the environmental pollutants derived from
chlorinated organic compounds will permeate into soil without
decomposition and gradually dissolve in ground water to expand the
contaminated area through ground water. Thus, it is strongly
desired to establish a technology for purifying the contaminated
environment to return it to the original state, in addition to
never cause such serious pollution again.
In one method to purify ground water, the contaminated ground water
is pumped up and purified on-site, by aerating the drawn ground
water in an aeration tower to pass the pollutant into the gas
phase. The pollutant in the gas phase is removed by an activated
carbon column not to cause air pollution by directly releasing the
gas into the air.
Purification methods utilizing degradation activities of
microorganisms, i.e., bioremediation, have bean also proposed to
purify ground water.
In connection with another purification method, Japanese Patent
Application Laid-Open No. 54-66376 discloses an apparatus where a
halide solution of NaCl or NaBr is electrolyzed in an electrolytic
bath, and the original gas containing a malodorous component is
passed through the catholyte and then through the anolyte to remove
the smell. With such an apparatus, however, malodorous gas may not
be treated steadily, because it includes three steps of aeration in
the anolyte, recovery of the gas, and aeration in the catholyte in
the process.
Japanese Patent Publication No. 53-17816 discloses a method of
treating an organic waste liquid, where aluminum chloride or iron
chloride is dissolved in the organic waste solution and the
chloride is electrolyzed under UV irradiation. According to the
specification, hypochlorous acid is generated from the electrolyzed
chloride and the organic compounds in the waste are decomposed by
active oxygen generated from hypochlorous acid by UV
irradiation.
This method also might not achieve a steady treatment, since the
chloride compound concentration in the waste will vary.
It is also known that a functional water can be obtained by
electrolyzing water. For example, acidic electrolyzed water has
sterilizing properties (Japanese Patent Application Laid-Open No.
1-180293) or can cleanse contaminants on semiconductor wafers (EP
605882A).
Photodecomposition is also known. For example, Japanese Patent
Application Laid-Open No. 9-299753 and No. 10-180040 disclose a
photodecomposition apparatus utilizing a phenomenon that UV-B, and
C can decompose certain pollutants.
SUMMARY OF THE INVENTION
The object of the present invention is to provide an apparatus that
can effectively purify contaminated water including ground water,
without secondary pollution problems, and not requiring activated
carbon or microorganisms. Another object of the present invention
is to provide a purification method using the apparatus.
One aspect of the present invention is an apparatus for purifying
contaminated water such as ground water.
According to one aspect of the present invention, there is provided
a purifying apparatus for water containing a pollutant comprising:
an aerator in which a contaminated water containing a pollutant is
aerated with a gas to generate a gas containing the pollutant; a
chlorine-containing gas generator that generates a
chlorine-containing gas; a mixing section where the
pollutant-containing gas generated from the contaminated water and
the chlorine-containing gas generated in the chlorine-containing
gas generator are mixed; and light-irradiation means for
irradiating the mixed gas with light to decompose the pollutant
contained in the mixed gas.
The purification apparatus for contaminated water of the present
invention is desirably constituted so that the aerator is in a
well.
The chlorine-containing gas generator that generates a
chlorine-containing gas includes, in addition to a chlorine
cylinder, aerators to aerate a functional water that generates
chlorine-containing gas by aeration. Specifically, an aerator to
blow air to the surface of the functional water, a jet device to
contacting the spray of functional water from a nozzle into contact
with air, or a bubbler can be preferably used.
The chlorine-containing gas generator may comprise a water tank,
means for generating functional water, means for introducing air
into the water tank, means for discharging a chlorine-containing
gas generated, and means for discharging the functional water used
for generating a chlorine-containing gas.
The means for generating functional water may comprise a water
tank, means for feeding an electrolyte-containing water into the
water tank, and a pair of electrodes and a power source to apply an
electric potential to the electrolyte-containing water in the water
tank.
According to another aspect of the present invention, there is
provided a method for purifying contaminated water comprising the
steps of: obtaining a pollutant-containing gas by aerating a
contaminated water containing a pollutant; obtaining a
chlorine-containing gas; mixing the pollutant-containing gas and
the chlorine-containing gas to form a mixed gas; decomposing the
pollutant in the mixed gas by irradiating with light the mixed gas
introduced into a treatment region in a treatment tank: and
discharging the mixed gas after decomposition treatment from the
treatment region.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 schematically illustrates a purifying apparatus for
contaminated water or ground water, being an embodiment of the
present invention;
FIG. 2 schematically illustrates a purifying apparatus of another
embodiment of the present invention;
FIG. 3 schematically illustrates a purifying apparatus of still
another embodiment of the present invention;
FIG. 4 schematically illustrates a purifying apparatus of still
another embodiment of the present invention;
FIG. 5 schematically illustrates an apparatus for purifying
contaminated ground water, being an embodiment of the present
invention; and
FIG. 6 schematically illustrates an apparatus for purifying
contaminated ground water, being an embodiment of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Now the present invention is described in detail.
The apparatus for purifying contaminated water according to the
present invention aerates contaminated water such as polluted
ground water (hereinafter, merely referred to as "contaminated
water") with a gas such as air to generate pollutant-containing
air. The apparatus also generates a chlorine-containing gas. The
pollutant-containing air and the chlorine-containing gas are mixed
before or after they were introduced into the treatment tank and
irradiated with light to decompose the pollutant (hereinafter the
pollutant refers to one or more pollutants decomposable in the
present invention). Thus, the purifying apparatus of the present
invention can efficiently remove the pollutant such as
trichloroethylene from contaminated water and decompose it.
Pollutants such as trichloroethylene are now causing serious
problems because of their harmful nature.
By using the apparatus of the invention, the pollutant removed from
the contaminated water is finally decomposed, and the contaminated
water is purified. Thus, the purification process is completed.
FIG. 1 schematically illustrates an apparatus for purifying
contaminated water according to one embodiment of the invention.
Here, contaminated water includes ground water contaminated with
halogenated aliphatic compounds such as organochlorinated
compounds. In this purifying apparatus, the pollutant is set free
from contaminated water and decomposed. This apparatus comprises an
aeration tank 2, a treatment tank 3 and light irradiation means 4.
Contaminated water 1 to be treated is contained in the aeration
tank 2, and aerated to discharge a gas containing the pollutant in
it. Chlorine-containing water is aerated with the gas discharged
from the aeration tank 2 to supply chlorine to the gas. Then the
gas containing the pollutant and chlorine is irradiated with light
in the treating tank 3 by using light-irradiation means 4.
Here, the aeration tank 2 is constituted in such a manner that
contaminated water can be fed thereto. The tank 2 may be provided
with stirring means 12 to efficiently aerate contaminated water
1.
In this purifying apparatus, contaminated water 1 is purified as
follows: the water 1 is put into the aeration tank 2 and a gas such
as air is sent by a pump 5 into the water 1 to set free the
pollutant from water 1. This step is called the aeration step.
The pollutant-containing gas discharged from the aeration step is
led into the treatment tank 3 by a pump 8 and passed through
chlorine-containing water (functional water).
Into the treatment tank 3, functional water is fed from a feeding
unit of functional water (not shown in the figure) through a pipe 9
by a pump 10. Then, the pollutant-containing gas from the aeration
tank 2 is passed through the functional water to be added with
chlorine. The gas containing both pollutant and chlorine is
photo-irradiated by using a lump as the light-irradiation means 4
and the pollutant is decomposed. This step is called purification
and decomposition step.
The functional water used in the treatment is discharged through a
discharge pipe 6, and the purified gas is discharged from a
discharge pipe 7. Numeral 12 denotes stirring means for stirring
contaminated water 1.
Further, a means for bringing the gas discharged from the discharge
pipe 7 in contact with an adsorption material like activated carbon
may be provided to adsorb any undecomposed pollutant.
Alternatively, the constitution may such that the gas from the
aeration tank 3 is once adsorbed and concentrated on the adsorption
material such as activated carbon, and then the gas released from
the adsorption material is introduced into the treatment tank
3.
FIG. 2 schematically illustrates an apparatus for purifying
contaminated water according to one embodiment of the invention.
Here, contaminated water includes ground water contaminated with
halogenated aliphatic compounds such as organochlorinated
compounds. In this purifying apparatus, the pollutant is removed
from contaminated water and decomposed. This apparatus comprises an
aeration tank 2, a functional water aeration tank (herein after
referred to as FW aeration tank) 14, a treatment tank 3 and light
irradiation means 4. Contaminated water 1 to be treated is
contained in the aeration tank 2, and aerated to discharge a gas
containing the pollutant in it. In the FW aeration tank,
chlorine-containing water is aerated to generate a
chlorine-containing gas. Then the gas containing the pollutant and
the gas containing chlorine is mixed and irradiated with light in
the treating tank 3 by using light-irradiation means 4.
Here, the aeration tank 2 is constituted in such a manner that
contaminated water can be fed thereto. The tank 2 may be provided
with stirring means 12 to efficiently aerate contaminated water
1.
In this purifying apparatus, contaminated water 1 is purified as
follows: the water 1 is put into the aeration tank 2 and a gas such
as air is sent by a pump 5 into the water 1 to free the pollutant
from water 1. This step is called the aeration step.
Next, a pollutant-containing gas is led into the treatment tank 3
with the use of the pump 8, and at the same time, a
chlorine-containing gas produced by passing through functional
water in the FW aeration tank 14 is introduced into the treatment
tank 3.
Functional water is fed into the FW aeration tank 14 from a
functional water production device (not shown in the figure)
through a pipe 9 and a pump 10. In the treatment tank 3,
light-irradiation is carried out by using a lamp as the
light-irradiation means 4 to decompose the pollutant in the mixed
gas. This process is referred to as a purification and
decomposition step. The functional water used in the FW aeration
tank 14 is discharged through a discharge pipe 6, and purified gas
is discharged from a discharged pipe 7.
Further, a means for bringing the gas discharged from the discharge
pipe 7 in contact with an adsorption material like activated carbon
may be provided to adsorb any undecomposed pollutant.
Alternatively, the constitution may such that the gas from the
aeration tank 3 is once adsorbed and concentrated on the adsorption
material such as activated carbon, and then the gas released from
the adsorption material is introduced into the treatment tank
3.
In the aeration step, in addition to stirring by the stirring
means, heating by using a heater etc. can accelerate gasification
of the pollutant.
Moreover, in a configuration shown in FIG. 3, a second treatment
tank 16 is provided for occasions when the pollutant still remains
in the gas discharged from an discharge pipe 7 after the treatment.
When chlorine gas remains in an amount sufficient for the second
treatment in the gas discharged from the discharge pipe 7, the
residual pollutant can be decomposed in a second treatment tank 16
by light-irradiation using light-irradiation means 17. When the
residual amount of chlorine gas in the discharged gas is
insufficient for the second treatment, chlorine-containing air is
fed from the FW aeration tank 14 (not shown in the figure) into the
second treatment tank 16 by a pump 18, and then, the residual
pollutant can be decomposed by light-irradiation.
In the embodiment shown in FIG. 4, part of the pollutant-containing
gas obtained by aerating contaminated water is used for aerating
functional water to generate a chlorine-containing gas. The
pollutant-containing gas is divided into two by a valve 20, one is
introduced into the treatment tank 3 and the other into the FW
aeration tank 14.
The gas introduced into the FW aeration tank 14 receives chlorine
from the functional water during passing through the functional
water to become a chlorine-containing gas, and then the gas is
introduced into the treatment tank 3 to be mixed with the
pollutant-containing gas that is directly introduced into the
treatment tank 3 via the valve 20. The pollutant is decomposed by
irradiation of the mixed gas with light by using the
light-irradiation means 4. Thus, contaminated water is
purified.
FIG. 5 illustrates an embodiment of the invention, an apparatus for
purifying ground water in a well dug into the soil. In the
apparatus shown in FIG. 5, the ground water that flows out in the
well 23 is purified.
First, the ground water that flowed out in the well 23 is aerated
by a blower 21 to pass the pollutant into the gas phase. The
pollutant-containing air is introduced into a treatment tank 33 by
a pump 22. Meanwhile, functional water prepared by a functional
water production device 30 is introduced into a FW aeration tank
28, into which air is blown from a blower 32. Chlorine-containing
gas obtained by aeration of functional water is introduced into a
treatment tank 33 through a pump 27 and is mixed with the
pollutant-containing air.
The mixed gas is irradiated with light by light-irradiation means
26 to decompose the pollutant and is then discharged from a
discharge pipe 34.
As the light-irradiation means 26 a black light may be used, for
example. The purified air from the discharge pipe 34 may be
discharged as it is when the pollutant concentration is not over
the prescribed limit, or it may be led into an adsorption column of
activated carbon.
In the configuration shown in FIG. 5, chlorine-containing gas
obtained by the aeration of functional water in an FW aeration tank
28 is introduced into a treatment tank 33 to be mixed with
pollutant-containing air and then the mixed gas is subjected to
decomposition. Alternatively, FIG. 6 shows a configuration in which
pollutant-containing air is mixed with chlorine from a chlorine gas
cylinder being a chlorine supplying device 35 to decompose the
pollutant in the mixed gas.
The process after the mixing of chlorine gas from a chlorine gas
cylinder is the same as shown in FIG. 5.
In the following, a more detailed description is provided.
<Contaminated Water to be Treated>
Contaminated water, including contaminated ground water, to be
treated in the present invention, is not specifically limited.
Subject pollutants to be treated in the present invention are those
decomposable by functional water and light, such as halogenated
aliphatic hydrocarbon compounds. The halogenated aliphatic
hydrocarbon compounds include those having at least one of chlorine
and fluorine atoms, especially, chlorinated organic compounds.
Chlorinated organic compounds include chloroethylene,
1,1-dichloroethylene, cis-1,2-dichloroethylene,
trans-1,2-dichloroethylene, trichloroethylene,
1,1,1-trichloroethane, tetrachloroethylene, chloromethane,
dichloromethane, trichloromethane and the like.
The present invention is suitable for treating pollutants that are
highly volatile and can easily pass into gas phase from
contaminated water by aeration, etc.
In addition to the ground water contaminated by the above-described
pollutants, the present invention can also be used to purify
desorption water that is produced when a gas containing any of the
above described pollutants is treated by activated carbon and the
adsorbed pollutants are desorbed by steam desorption or the
like.
Contaminated water of any pollutant concentration may be used in
the present invention, that is, contaminated water of a pollutant
concentration from as low as 1 mg/L or less to as high as 100%,
almost neat, can be treated.
<Functional Water Generation Unit and Functional Water>
Functional water, which can be used in the present invention and
can generate a chlorine-containing gas by aeration, is a chlorine
solution having the following properties. Such a solution is called
electrolyzed water or electrolyzed functional water and is being
used for the purpose of sterilization. Functional water as used
herein refers to water having a pH between 1 and 4 and a residual
chlorine concentration between 5 mg/liter and 150 mg/liter,
preferably between 30 mg/liter and 120 mg/liter. Preferably, the
functional water has an oxidation-reduction potential between 800
mV and 1,500 mV when measured by using platinum and silver-silver
chloride as the working and the reference electrodes,
respectively.
Functional water can be obtained near the anode when an electrolyte
(e.g. sodium chloride or potassium chloride) is dissolved into the
source water and the solution is electrolyzed in a water tank
provided with a pair of electrodes.
For preparing functional water having the above properties, the
concentration of the electrolyte, e.g., sodium chloride, in the
source water before the electrolysis is preferably between 20 mg/L
and 2,000 mg/L.
Undesired mixing of the acidic functional water produced around the
anode and the alkaline water produced around the cathode can be
prevented by providing a diaphragm between the paired
electrodes.
Such a diaphragm may suitably be an ion exchange membrane. To
obtain such functional water, any commercially available strongly
acidic electrolytic water generator (e.g., OASYS Bio HALF: trade
name, a product of Asahi Glass Engineering, or Strong Electrolytic
Water Generator Model FW-200: trade name, a product of Amano) may
be used.
Functional water having above properties can be prepared by using
reagents such as sodium hypochlorous acid. For example, an aqueous
solution containing 0.001 to 0.1 mol/l hydrochloric acid, 0.005 to
0.02 mol/l sodium chloride and 0.0001 to 0.1 mol/l sodium
hypochlorite can be used as a functional water.
Also, functional water of a pH not higher than 4.0 and of a
chlorine concentration 2 mg/L to 2000 mg/L may be prepared from
hydrochloric acid and sodium hypochlorite. For example, a solution
containing 0.001 to 0.1 mol/l hydrochloric acid and 0.0001 to 0.01
mol/l sodium hypochlorite.
Hydrochloric acid may be replaced by some other inorganic acid or
by an organic acid. Inorganic acids that can be used for the
purpose of the invention include hydrofluoric acid, sulfuric acid,
phosphoric acid and boric acid, whereas organic acids that can be
used for the purpose of the invention include acetic acid, formic
acid, malic acid, citric acid and oxalic acid. A commercially
available weak acidic functional water-generating powder (e.g.,
Kino-san 21X: trade name, a product of Clean Chemical) typically
containing N.sub.3 C.sub.3 O.sub.3 NaCl.sub.2 may also be used for
preparing functional water.
Functional water produced by an electrolysis apparatus without a
diaphragm is also used for decomposing organochlorinated compounds.
For example. electrolyzed water having a redox potential not lower
than 300 mV and not higher than 1100 mV, and a chlorine
concentration not lower than 2 mg/L, and pH 4 to 10 can be
used.
Functional water of a pH higher than 4 can be prepared not only by
electrolysis but also by dissolving various reagents into source
water. For example, desired chlorine-containing water can be
obtained by dissolving hydrochloric acid to 0.001 to 0.1 mol/l,
sodium hydroxide to 0.001 to 0.1 mol/l and sodium hypochlorite to
0.0001 to 0.01 mol/l.
Alternatively, chlorine-containing water of a pH not lower than 4
and of a chlorine concentration not higher than 1000 mol/l can be
obtained by using hypochlorite singly, for example, by dissolving
sodium hypochlorite to 0.0001 to 0.01 mol/l.
The above description of functional water is for a configuration
mainly shown in FIG. 1, where a means for generating
chlorine-containing air comprises an aeration tank containing
chlorine-containing water (functional water) in it and aeration
means to aerate air containing the pollutant into it, and this
aeration means also works as a mixing means of the
chlorine-containing air and the pollutant-containing gas.
As described later, in the present invention, it is desirable that
chlorine is present in a certain concentration range in the site of
the decomposition, and as long as this concentration range is
fulfilled, the chlorine concentration in the functional water in
the means for generating chlorine-containing air is not necessarily
in the above-described range.
For example, as shown in FIG. 2, when air containing no pollutant
is introduced in functional water and then generated chlorine gas
and pollutant-containing air are mixed, it is desirable to increase
the chlorine concentration in the functional water. That is, in
such a constitution as shown in FIG. 2, the generated chlorine gas
is diluted with pollutant-containing air. The dilution degree
depends upon the ratio of the amounts of generated chlorine gas and
the pollutant-containing air introduced into the reaction site. For
example, if the pollutant-containing air is introduced 4 times as
much as the generated chlorine gas, the concentration of chlorine
is diluted to 1/5. To maintain the chlorine concentration at a
certain level even with such dilution in a configuration as FIG. 2,
it Is desirable to increase the chlorine concentration in the
functional water.
Functional water of a higher chlorine concentration (a chlorine
solution) can be prepared easily by using reagents, in comparison
with electrolysis, that is, it is easy to obtain functional water
having a chlorine concentration 10 to 50 times higher than that of
the functional water obtained by electrolysis, e.g., a functional
water of residual chlorine concentration range of not less than 50
mg/L and not higher than 15000 mg/L, less, preferably not less than
50 mg/L and not higher than 3000 mg/L, and more preferably not less
than 100 mg/L and not higher than 1500 mg/L. Although it is not
agreed whether a solution having such a high residual chlorine
concentration of remaining chlorine can be called functional water,
in the present invention such solutions are also included in
functional water. When functional water having such a high
concentration of residual chlorine is prepared from reagents, it is
better to mix, for example, hydrochloric acid and sodium
hypochlorite are mixed in situ in a chlorine-generating tank (a FW
aeration tank) rather than mixing reagents in advance.
Here, source water to be used for preparing functional water
includes city water, river water, sea water etc., of which pH is
usually between 6 and 8 and the chlorine concentration is less than
1 mg/L utmost. Thus, such source water by itself cannot decompose
chlorinated organic compounds as mentioned above
As discussed below, as long as the chlorine concentration in the
mixed gas can be achieved, functional water is not limited to the
above described functional water.
<Concentration of Chlorine Gas and Means for Generating Chlorine
Gas>
From all of the above described functional water, it is possible to
generate chlorine gas that is needed to decompose the pollutant. As
a chlorine-containing gas, one can use chlorine-containing air
which is obtained by passing air through functional water. In one
embodiment of the present invention, this gas is mixed with a gas
to be decomposed and then photo-irradiated to decompose the
pollutant.
Alternatively, a mixture of chlorine-containing gas and a gas to be
decomposed can be obtained by passing pollutant-containing air
instead of air through functional water. In this case, a mixed gas
of relatively high chlorine concentration can be obtained.
It does not matter that the air to be passed through the functional
water or to be blown on the surface of the functional water
contains the pollutant, that is, it may be the air obtained by
aerating contaminated ground water etc. However, in this case, care
should be taken because the pollutant may partly dissolves into
functional water. In such a case, it is desirable to provide means
for irradiating the drained functional water with light.
Concerning the mixing ratio of the gas to be decomposed and the
chlorine-containing gas, the gaseous chlorine concentration is
preferably not lower than 5 ppm and not higher than 1000 ppm. The
decomposition efficiency of the gaseous pollutant to be decomposed
becomes high, especially when the gaseous chlorine concentration in
the gas mixture is between 20 ppm and 500 ppm, more preferably
between 80 ppm and 300 ppm, though depending upon the concentration
of the pollutant.
As described above, such gaseous chlorine can be generated and
supplied by electrolysis or by using chemicals. In addition,
chlorine gas of desired concentration can be directly obtained by
diluting concentrated chlorine gas in a chlorine gas bomb, a
chlorine gas cartridge or the like. That is, the best method can be
chosen from these methods according to the conditions, so long as
the chlorine concentration in the gas mixture is in the range as
described above.
So far, only chlorine gas has been described as the gas for
decomposition, but other halogen gases can be used so long as they
can generate radicals by light-irradiation.
<Light-irradiating Means>
The light-irradiation means that can be used in the present
invention irradiates light of, preferably 300 to 500 nm in
wavelength, more preferably 350 to 450 nm in wavelength. Concerning
the intensity of irradiation to a mixture of chlorine gas and the
target substance to be decomposed with a light, for example, from a
light source with a peak wavelength of 365 nm, an intensity of
several hundreds .mu.W/cm.sup.2 (as measured in a wavelength range
between 300 nm and 400 nm) Is sufficient for decomposing the target
substance in practical applications.
Either natural light (e.g., sun light) or artificial light (light
from a mercury lamp, a black lamp or a color fluorescent lamp,
short wavelength (<500 nm) light-emitting diode etc.) can be
used.
As shown in FIG. 1, when the used chlorine-containing water is
drained off, the drainage may be light-irradiated. In this case,
irradiation means of the above-described wavelength, intensity,
light source is desirably used.
<Reaction Tank>
Any form may be used to physically limit the treatment region where
the decomposition treatment is carried out. As mentioned above,
purification reaction proceeds without the light having a short
wavelength of 300 nm or below. Thus, glass, plastics or the like
not permitting such light can be used.
Thereby it is possible to constitute an inexpensive system.
Gas discharged from the reaction tank after light-irradiation
treatment may be introduced into the second reaction tank of a
constitution similar to the first reaction tank to be
light-irradiated again. It is also possible to arrange reaction
tanks in tandem until the gas reaches to a sufficiently purified
level.
Because of the wider choice of the material, the degree of freedom
in forms and shapes of the reaction tank is also increased. For
example, a bag-like container such as an air bag can be used as a
reaction tank.
Any form of a bag-shaped reaction tank can be used as long as light
needed for the decomposition 300 nm or more, or 350 nm or more in
wavelength) can pass through It. In particular, TEDLAR bag using
polyvinyl fluoride film (TEDLAR: trade name of Du Pont Co., Ltd.)
or fluororesin bag or the like are suitable in view of gas
adsorption and permeability.
By using a bag as a reaction tank, not only the apparatus becomes
cheap, but also the installation in the treatment site, movement
and removal of apparatus become easy because of the light
weight.
Further, by adopting bellows constitution, the reaction tank can be
easily folded.
Because it is easy to change the size in conformity with
decomposition conditions for the reaction tank of bellows-like or
bag-like constitution, the most suitable retention time (reaction
time) can be variably set according to the conditions.
<Means for Aerating Functional Water and Contaminated
Water>
To aerate water with air, or to aerate functional water with
pollutant-containing gas and/or aeration gas, an air diffuser
(bubbler) can be used. It may be an ordinary air-diffuser used for
blowing a gas through a liquid, but desirably used is a diffuser
that can produce bubbles having a surface area sufficient to set
chlorine free.
It is desirable that the diffuser is made of a material not
reactive with the components in functional water. For example,
usable diffusers include porous diffusion plates made of sintered
glass, porous ceramics, sintered SUS316, or a net of fibrous
SUS316, and spargers made of pipes of glass, SUS316 or the
like.
<Main Reaction Site in the Decomposition Process>
In one embodiment of the present invention, chlorine-containing air
required for decomposition is generated by passing air through
functional water. This part supplies chlorine gas that is
indispensable for decomposition. Subsequent gaseous reaction in a
tank for treatment and decomposition is the main part of
decomposition reaction.
For this reason, when the chlorine generation unit and the
decomposition reaction unit are integrated into one unit, the ratio
of the gas phase part and liquid phase part exerts a strong
influence on the decomposition capacity. That is, if the volume of
functional water is increased to increase the chlorine supply, the
gas phase part is decreased decreasing the decomposition reaction
site. On the other hand, if the gas phase part is increased to
increase the reaction site, decomposition reaction proceeds
rapidly, but this means decrease of the liquid phase, resulting in
the decrease of chlorine supply.
When chlorine-containing gas generation and the decomposition
reaction are carried out in one treatment unit, the percentage of
the liquid phase in the treatment unit is better to be from 5% to
30%, desirably from 10% to 20%, although many factors such as the
aeration rate and the feeding rate of functional water may affect.
When these reactions are carried out in separate units, the volume
ratio of the tanks is desirably about 1:2 to 1:9.
<Decomposition Reaction Mechanism>
The inventors of the present invention have already found that the
decomposition of a chlorinated organic compound proceeds when the
compound is light-irradiated in the presence of chlorine gas, but
the reaction mechanism is mostly unknown. It is already known that
when irradiated with light of a specific wavelength range, chlorine
dissociates and generates radicals. Thus, in the present invention,
it is considered that chlorine radicals are generated from chlorine
by light-irradiation to react with the compound to be decomposed
cleaving the bond.
For example, when functional water is generated around the anode by
electrolyzing water containing an electrolyte such as sodium
chloride, it contains hypochlorous acid or hypochlorous acid ion.
Since such functional water containing hypochlorous acid or
hypochlorous acid ion is acidic, it is considered that chlorine
increases in this functional water. When the functional water is
light-irradiated, chlorine radicals are generated from chlorine by
excitation, which cause the decomposition reaction of
pollutant.
When functional water is aerated, chlorine in the functional water
passes into the gas phase. Chlorine and the pollutant are mixed in
the gas phase. When this mixed gas is light-irradiated, chlorine is
excited to form radicals and the decomposition reaction of the
pollutant proceeds. On this account, it is assumed that most of the
decomposition proceeds in gas phase than in liquid phase.
Furthermore, oxygen is essential in the reaction of the present
invention, but the oxygen radicals produced by the electrolysis of
sodium chloride and water and oxygen in the air are sufficient for
the reaction.
As above, descriptions have been made mainly about the purification
of ground water, the present invention can be also applied to the
purification of any water contaminated with pollutants including
the above described chlorinated organic compounds.
For example, the present invention is suitable for purifying the
desorption water that is produced in regenerating the activated
carbon used in the purification process of contaminated gas to
adsorb and remove the pollutant.
EXAMPLE
In the following, the present invention will be described
concretely with reference to examples.
Example 1
Contaminated water was purified by using a purifying apparatus for
contaminated water shown in FIG. 2.
Contaminated water 1 contaminated with chlorinated organic
compounds was fed to a stainless steel aeration tank 2.
Pollutants and their concentrations in the contaminated water were
as follows.
Trichloroethylene 22.3 mg/kg Tetrachloroethylene 5.7 mg/kg
cis-Dichloroethylene 2.0 mg/kg 1,1-Dichloroethylene 0.5 mg/kg
The contaminated water in the aeration tank 2 was aerated by air
fed from the pump 5 to desorb the pollutant into the gas phase.
Then, the pollutant-containing air was led to a treatment tank 3
and was mixed with chlorine-containing air fed from a FW aeration
tank 14 in the treatment tank 3.
In this Example, a strongly acidic functional water generating
apparatus (OASYS Bio HALF ADE-61: tradename, a product of Asahi
Glass Engineering) was used to produce functional water having a pH
of 2.1, an oxidation-reduction potential of 1,150 mV and a residual
chlorine concentration of 50 mg/L.
The inside of the treatment tank 3 was irradiated with black light
emitted from light irradiation means 4 (Black Light Fluorescent
Lamp FL20BLB: tradename, a product of Toshiba, 20 W). The treatment
tank 3 is a glass column not transmit the light having a wavelength
of 300 nm or shorter.
The concentrations of pollutants in the gas discharged from
discharge pipe 7 were determined by gas chromatography using a gas
chromatograph with an FID detector (GC-14B: a product of Shimadzu
Seisakusho, DB-624 column: a product of J & W Co., Ltd.) to
find that all pollutants were under the detection limit. The
treated contaminated water was immediately taken into a tank
containing n-hexane and stirred for 10 minutes. Then, the n-hexane
layer was collected and subjected to ECD gas chromatography. None
of the pollutants were present at a concentration higher than 0.01
mg/kg.
As a result, it was confirmed that the contaminated water was
purified and pollutants released from the contaminated water were
decomposed.
Example 2
Contaminated water was purified by using a purifying apparatus for
contaminated water shown in FIG. 3.
Contaminated water 1 contaminated with chlorinated organic
compounds was fed to a stainless steel aeration tank 2.
Pollutants and their concentrations in the contaminated water were
as follows.
Trichloroethylene 102.6 mg/kg Tetrachloroethylene 15.7 mg/kg
cis-Dichloroethylene 20.2 mg/kg 1,1-Dichloroethylene 12.5 mg/kg
The pollutant-containing air and chlorine-containing air were mixed
in the same manner as in Example 1 and the treatment tank 3 was
light-irradiated with black light rays by a light-irradiation means
4. The pollutant concentrations were measured in the same manner as
in Example 1. As a result, the pollutant concentrations in the
discharge pipe 7 were as follows. From these results, pollutants
were still present there.
Trichloroethylene 17.2 ppm Tetrachloroethylene 1.1 ppm
cis-Dichloroethylene 0.9 ppm 1,1-dichloroethylene 0.5 ppm
In this Example, the discharged air still containing the pollutants
as above was fed to a second treatment tank 16 and was subjected to
purification treatment again with the use of a black light of photo
irradiation means 17. This time, chlorine-containing air was fed to
the second treatment tank 16 using a pump 18 to adjust the chlorine
concentration in the treatment tank to about 50 ppm.
The pollutant concentrations in a gas discharged from a discharge
pipe 19 were determined by the same method as in Example 1. All
pollutants were under the detection limits and the pollutant
concentrations in the treated contaminated water were 0.01 mg/kg or
below. Thus, it was confirmed that contaminated water was purified
and pollutants released from the contaminated water were
decomposed.
Example 3
Contaminated water was purified with an apparatus shown in FIG.
4.
Although the apparatus used in this example is almost the same as
that used in Example 1 except that part of pollutant-containing air
fed from the aeration tank 2 was used to aerate the FW aeration
tank 14 with the valve 20, where in Example 1, air was fed to the
FW aeration tank 14 by the pump 15.
Properties of functional water, light-irradiation means,
measurement methods of pollutants in air discharged from the
discharge pipe 7 and others are the same as in Example 1.
When the pollutant concentrations in the gas discharged from the
discharge pipe 7 were measured by the same method as in Example 1,
all pollutants were below the detection limits and the pollutant
concentrations in the treated contaminated water were all 0.01
mg/kg or below. Thus, it was confirmed that contaminated water was
purified and pollutants released from the contaminated water were
decomposed.
Example 4
Contaminated water desorbed from activated carbon was purified by
using the purifying apparatus shown in FIG. 2.
Pollutant-adsorbing activated carbon that had been recovered from
an adsorption column filled with activated carbon was used. The
activated carbon was desorbed with steam and resultant desorbed
contaminated water 1 that contains chlorinated organic compounds
was fed to the stainless steel aeration tank 2.
Polluting components and their concentration in the contaminated
water were as follows.
Trichloroethylene 72.3 mg/kg Tetrachloroethylene 5.1 mg/kg
cis-1,2-Dichloroethylene 12.3 mg/kg 1,1-Dichloroethylene 10.5
mg/kg
The contaminated water fed to the aeration tank 2 was aerated by
air fed from the pump 5 to desorb pollutants into the gas phase.
Then, the pollutant-containing air was led to the treatment tank 3
and mixed with chlorine-containing air fed from the FW aeration
tank 14.
In this Example, a strongly acidic functional water generating
apparatus (OASYS Bio HALF ADE-61: tradename, a product of Asahi
Glass Engineering) was used to produce functional water having a pH
of 2.1, an oxidation-reduction potential of 1,150 mV and a residual
chlorine concentration of 50 mg/L.
The inside of the treatment tank 3 was irradiated with black light
emitted from light irradiation means 4 (Black Light Fluorescent
Lamp FL20BLB: tradename, a product of Toshiba, 20 W). The treatment
Lank 3 is a glass column not transmit the light having a short
wavelength of 300 nm or shorter.
The concentrations of pollutants in the gas discharged from
discharge pipe 7 were determined by gas chromatography using a gas
chromatograph with an FID detector (GC-14B: a product of Shimadzu
Seisakusho, DE-624 column: a product of J & W Co., Ltd.) to
find that all pollutants were under the detection limit. The
treated contaminated water was immediately taken into a tank
containing n-hexane and stirred for 10 minutes. Then, the n-hexane
layer was collected and subjected to ECD gas chromatography. None
of the pollutants were present at a concentration higher than 0.01
mg/kg.
As a result, it was confirmed that the contaminated water was
purified and pollutants released from the contaminated water were
decomposed.
Example 5
An experiment was carried out in the same manner as in Example 4,
except that the FW aeration tank 14 in FIG. 2 was replaced with an
chlorine gas cylinder.
Chlorine gas from the cylinder was fed to the treatment tank 3 to
be mixed with the pollutant-containing air therein.
The inside of the treatment tank 3 was irradiated with black light
emitted from light irradiation means 4 (Black Light Fluorescent
Lamp FL20BLB: tradename, a product of Toshiba, 20 W). The treatment
tank 3 is a glass column not transmit the light having a wavelength
of 300 nm or shorter.
The concentrations of pollutants in the gas discharged from
discharge pipe 7 were determined by gas chromatography using a gas
chromatograph with an FID detector (GC-14B: a product of Shimadzu
Seisakusho, DB-624 column: a product of J & W Co., Ltd.) to
find that all pollutants were under the detection limit. The
treated contaminated water was immediately taken into a tank
containing n-hexane and stirred for 10 minutes. Then, the n-hexane
layer was collected and subjected to ECD gas chromatography. None
of the pollutants were present at a concentration higher than 0.01
mg/kg.
As a result, it was confirmed that the contaminated water was
purified and pollutants released from the contaminated water were
decomposed, even when the FW aeration tank is replaced with a
chlorine gas cylinder.
Example 6
In this Example, a light source having a wavelength peak at 254 nm
(germicidal lamp) was used as the light-irradiation means instead
of the light source having a wavelength peak at 300 nm to 500 nm
used in Examples 1 to 5, That is, as the light-irradiation means in
the purifying apparatus shown in FIG. 1, a germicidal lamp sheathed
in a silica tube is installed in the treatment tank 3 to irradiate
UV light instead of black light. Next, the decomposition experiment
was carried out under two conditions: the aeration tank 2 was
filled with functional water to feed chlorine-containing air to the
treating tank, or the aeration tank 2 was filled with pure water to
feed air to the treatment tank, to compare the decomposition
efficiency between these conditions. As a result, under UV
irradiation, the decomposition capacity was 2 to 20 times higher
when the chlorine gas was fed. This effect is conspicuous in
decomposing low concentration pollutant of 10 ppm or less, further
increasing decomposition capacity.
As described above, the present invention of apparatus and method
for purifying contaminated water enables essential decomposition of
pollutants, especially halogenated aliphatic hydrocarbon compounds
contained in contaminated water at low cost, not merely moving the
pollutant from one medium to another medium, e.g., from the
contaminated water to activated carbon.
Moreover, the chlorine-containing gas generation device of the
present invention can generate a chlorine-containing gas with high
controllability and stability.
In addition, the contaminated gas decomposition apparatus of the
present invention provided with this chlorine-containing gas
generation device can decompose contaminated gas with high
controllability and stability.
* * * * *